The free gingival groove is most commonly associated with which tooth? PGCEE MDS Entrance 2025

 # The free gingival groove is most commonly associated with which tooth? 

a) Maxillary canine 

b) Mandibular incisor 

c) Maxillary first molar 

d) Mandibular premolar

The correct answer is:

b) Mandibular incisor

The free gingival groove is a shallow linear depression that demarcates the free gingiva from the attached gingiva. It is more prominent in some individuals and may not always be present. However, when it is visible, it is most commonly associated with the mandibular incisors due to their relatively thin and well-defined gingival anatomy. This aligns with standard dental textbooks like Carranza’s Clinical Periodontology, which highlights the mandibular incisors as a common site for the free gingival groove.

Well aligned deciduous dentition is an indication of: PGCEE MDS Entrance 2025

 # Well aligned deciduous dentition is an indication of:

A. Potential crowding

B. Disto occlusion

C. Mesio occlusion

D. Well aligned permanent teeth

The correct answer is:

A. Potential crowding

Explanation:

• Well-aligned deciduous dentition (primary teeth) with little to no spacing is often a predictor of potential crowding in the permanent dentition.

• Primary teeth are smaller than permanent teeth, and deciduous arches typically exhibit natural spacing ("primate spaces") to accommodate the larger permanent successors. If primary teeth are tightly aligned, it suggests insufficient space for the eruption of larger permanent teeth, increasing the risk of crowding.

• D. Well-aligned permanent teeth is incorrect because spaced (not tightly aligned) primary teeth are actually a better indicator of sufficient arch space for proper alignment of permanent teeth.

• B. Disto-occlusion and C. Mesio-occlusion refer to malocclusions (Class II and Class III bites, respectively) and are unrelated to primary tooth alignment.

Key Takeaway: Tightly aligned primary teeth (lacking spacing) often signal future crowding, as permanent teeth require more space. Spaced primary dentition is ideal for alignment of permanent teeth.

The palate is considered the most appropriate insertion site for miniscrews supporting an intraoral distalizer because it:

 # The palate is considered the most appropriate insertion site for miniscrews supporting an intraoral distalizer because it:

a) is free of dental roots and other anatomical structures

b) does not create a force vector passing coronally to the maxillary arch’s center of resistance

c) takes advantage of bicortical anchorage

d) all of the above

The correct answer is D. All of the above

Explanation:

The palate is an ideal site for miniscrew-supported intraoral distalizers because of the following advantages:

1. Free of dental roots and other anatomical structures (Option a)

   • The mid-palatal region is a safe zone with minimal risk of damaging dental roots or vital structures, making it ideal for miniscrew placement.

2. Does not create a force vector passing coronally to the maxillary arch’s center of resistance (Option b)

   • Placing miniscrews in the palate helps direct force closer to the center of resistance of the maxillary arch, reducing unwanted tipping or extrusion effects.

3. Takes advantage of bicortical anchorage (Option c)

   • The palatal bone is thick and dense, allowing for bicortical engagement (penetration into both the cortical and cancellous bone), which improves primary stability and resistance to failure.

Since all of the statements are true, option d (all of the above) is the correct answer.

Intraoral Class II distalizers have the major disadvantage of:

 # Intraoral Class II distalizers have the major disadvantage of:

a) the need for patient compliance

b) a force vector passing coronally to the maxillary arch’s center of resistance

c) anterior anchorage loss

d) an inability to be used simultaneously with multibracket appliances

The correct answer is:

c) Anterior anchorage loss

Explanation:

Intraoral Class II distalizers, such as the Pendulum appliance, Distal Jet, or Forsus, rely on posterior force application to move the maxillary molars distally. However, a major drawback is anterior anchorage loss, meaning:

As the maxillary molars move distally, the anterior teeth tend to drift forward, leading to proclination of the incisors.

This can compromise the correction of a Class II malocclusion if not properly controlled with anchorage reinforcement.

Why not the other options?

(a) The need for patient compliance → Not true for most fixed distalizers (e.g., Pendulum, Distal Jet), but true for removable appliances like elastics or headgear.

(b) A force vector passing coronally to the maxillary arch’s center of resistance → This is a concern in some cases but not the primary disadvantage.

(d) An inability to be used simultaneously with multibracket appliances → Many distalizers can be used alongside braces (e.g., Forsus, Carriere Motion Appliance).

The Invisalign Palatal expander is directly printed from:

 # The Invisalign Palatal expander is directly printed from:

a) polyamide-12

b) TC-85

c) polymethyl methacrylate

d) thermoplastic polyurethane

The correct answer is A. Polyamide-12.

The Invisalign Palatal Expander (IPE) is 3D-printed directly from Polyamide-12 (PA-12), a biocompatible and durable nylon-based material. This material is widely used in medical applications due to its strength, flexibility, and resistance to wear. PA-12 allows for precise and customized expansion while maintaining patient comfort.

The Invisalign Palatal Expander (IPE) is designed to expand the dentition in increments of:

  # The Invisalign Palatal Expander (IPE) is designed to expand the dentition in increments of:

a) 0.1mm

b) 0.25mm

c) 0.5mm

d) 1mm

The correct answer is B. 0.25 mm.

The Invisalign Palatal Expander (IPE) uses a series of custom-designed, 3D-printed expansion trays to gradually widen the upper arch. It expands the dentition in controlled increments of 0.25mm per adjustment, ensuring a more comfortable and predictable expansion compared to traditional rapid palatal expanders (RPEs).

Following are "essential diagnostic criteria" according to Graber except:

 # Following are "essential diagnostic criteria" according to Graber except:

a) Case history

b) Facial photographs

c) Periapical x-rays

d) Lateral cephalograms

The correct answer is:

d) Lateral cephalograms

Graber's essential diagnostic criteria for orthodontic diagnosis typically include case history, facial photographs, and periapical x-rays. Lateral cephalograms, while useful for orthodontic analysis, are not considered part of the essential diagnostic criteria according to Graber.